We are interested in the mechanisms of ion transport and the control of these mechanisms in mammalian (piglet) gastric mucosa. Since we have found that tissue cyclic AMP content increases quite dramatically after histamine stimulation of H ion secretion, we will be interested in monitoring c-AMP levels under conditions in which we have altered intracellular and/or extracellular (Ca ions) and also after addition of prostaglandins E1 and/or E2. Wash-out kinetics of 45Ca ions will also be performed. We thus hope to gain insights into the interactions between histamine, Ca ions, c-AMP and prostaglandins in the control of gastric H ion secretion. Another portion of our work will be concerned with analyzing Cl-secretion by this tissue. We have hypothesized that Cl- secretion is mediated by a serosal membrane "carrier" which requires the presence of Na ion in the serosal solution. To test the hypothesis will require measuring intracellular ionic (Cl-, NA ion, and K ion) concentrations using radioisotopes, chemical determinations, and ion specific electrodes. We will test the effects of NA ion-free solutions as well as common transport and metabolic inhibitors. Finally, since a detailed study of the anion selectivity of the various transport mechanisms have never been performed in gastric mucosa, we will do this. We will be interested in the relative preferance for anions of the current-generating mechanism the conductance of the apical and basal membranes, the exchange diffusion process, and the H ion-coupled anion secretion. These studies will offer insights into the relationships between these different processes.